1. Field of the Invention
The present invention relates to an endovascular prosthesis.
2. Description of the Related Art
Endovascular prostheses are devices which are to be positioned inside blood vessels in order to treat aneurysmal lesions, especially in the region of the aorta.
Such prostheses are generally of tubular shape and conventionally comprise a rigid (generally metal) support structure, commonly known by the name “stent”, which is covered with a synthetic fabric. Such prostheses are also known by the name vascular endoprostheses or “stent-grafts”. The fabric covering the rigid support is chosen to replace the vascular wall at least partially.
It is known that, in humans, aneurysms can damage health. An aneurysm is the formation of one or more local cavities (or sacs) in the region of the wall of an artery or of a vein. These cavities fill with blood while being in communication with said artery or vein. A major risk associated with the formation of these cavities is the possibility that they may rupture. This is referred to as rupture of the aneurysm, which can lead to internal bleeding. Internal bleeding is a dangerous event which can lead to death by exsanguination.
In the art, an aneurysm can be defined as the loss of parallelism of the wall of a vessel. In other words, the walls are dilated and behave like a sac which has lower strength but is nevertheless exposed to blood pressure. As mentioned above, the main complication of aneurysms is rupture, which results in death in more than 80% of cases.
Accordingly, treatment by endovascular prosthesis aims essentially to preserve an intact blood circulation. The principle of the treatment is to exclude the aneurysmal cavity from the blood flow. This is achieved by positioning an endovascular prosthesis in the damaged artery or vein in the region of the aneurysmal cavity. More precisely, the endovascular prosthesis is arranged to fit the inside wall of the damaged artery or vein, in the region of the blood vessel-aneurysmal cavity junction. The blood vessel is thus made leak-tight with respect to the aneurysmal cavity.
The endovascular prosthesis is interposed between the healthy upstream artery and the healthy downstream artery, or the proximal neck and the distal neck, respectively. The endovascular prosthesis thus forms a leak-tight channel which acts as an artificial vessel while excluding the aneurysmal cavity.
An endovascular prosthesis is introduced by known angioplastic techniques. Among those techniques there may be mentioned especially catheterisation or arterial navigation. These techniques make it possible to avoid conventional surgery, called “open surgery”, which is more invasive and which often requires the thorax or the abdomen to be opened.
Conventional endovascular prostheses thus permit the treatment of aneurysms located away from regions of origin of collaterals. However, aneurysms located close to regions of origin of collaterals (in particular close to collaterals of vital or functional importance) are more difficult to treat. Indeed, treatment by endovascular prosthesis must keep the blood supply (or perfusion) of the collaterals intact.
Aortic aneurysms are among the disorders which can be treated by means of endovascular prostheses. However, the aorta has a complex anatomy, especially at the origin of essential collaterals such as the brachiocephalic arterial trunk, the blood flow of which, which irrigates the head, must be preserved. Treatment of an aortic aneurysm by endovascular prostheses must therefore preserve an intact blood supply in the region of each bifurcation zone.
This can be achieved only with difficulty. Moreover, each patient has an anatomy which is unique to him. The endovascular prostheses known in the art are thus generally custom-made, taking account of the patient's anatomy.
The prostheses of the prior art have a steric hindrance which makes them difficult to manipulate. This gives rise to difficulties during their positioning in the body of a patient, especially in the region of considerable arterial curvature.
The scientific publication “Fenestrated and branched devices in the pipeline; Greenberg and Qureshi; Journal Of Vascular Surgery, Volume 52, Number 13S, 2010” discloses endovascular prostheses known in the prior art.
Document WO 2009/102441 A1 describes an endovascular prosthesis suitable for being placed in a curved region of the aorta. The prosthesis does not provide bifurcation.
Document WO 2008/107885 A2 describes an endovascular prosthesis system for generating a bifurcation in the region of the aorta.
Document WO 2011/070576 A1 describes an endovascular prosthesis system for generating a crossing in the region of the aorta.